I'd set up some cavaletti exercises or canter pole exercises. If you do set some up, make sure you're fully sitting down and making her CANTER over them, not letting her jump them!
Also, lots of transitions. A lot. Walk-trot, trot-canter, whatever, as long as they're QUALITY transitions and she's pushing through and over her back in them. I like doing a lot of trot-walk-trot transitions to really help them build up muscle and start pushing through. Make sure you have a good walk and a good trot before you expect a good canter! The quality of each gait builds off of the one below it.
"Always be yourself. Unless you can be a unicorn. Then, always be a unicorn."